SDF Public Access Unix System

SDF provides free Unix shell access, web hosting and many other features at the user membership level.

Additional programs, capabilities and resources are available at "patron" and "sustaining" level memberships, which are granted with one-time or recurring dues in support of the SDF system.

[14] SDF also supports multiple retrocomputing experiences, including free user accounts on TOPS-20 and Symbolics Genera operating systems that are running live and accessible via the internet.

There are also specialized privileges which patron and sustaining level users can obtain to gain access to particular technologies, including mailing lists, Voice-over-IP, Databases, Virtual Private Network (VPN), and Domain registration.

In 1987, Ted Uhlemann started SDF on an Apple IIe microcomputer running "Magic City Micro-BBS" under ProDOS.

In 1989, Uhlemann and Stephen Jones operated SDF very briefly as a DragCit Citadel BBS before attempting to use an Intel x86 UNIX clone called Coherent.

Although SDF Public Access UNIX System was registered as an operating business in 1993 according to the Dallas County Records Office, it wasn't until October 1, 2001, that the SDF Public Access UNIX System was formed as a Delaware not-for-profit corporation and subsequently granted 501(c)(7) non-profit membership club status by the IRS.